1. Field of the Invention
The present invention relates to a tape cassette having a tape guide for prolonging a life of a tape.
2. Description of the Prior Art
A guide is known for guiding a running of a tape which is disposed in a tape cassette or cartridge having at least one reel for winding the tape in a case.
In the conventional auido tape cassette, the guide has usually consisted of a roller and a fixed pin made of a plastic.
It has been well-known that the wearing of the fixed pin made of a plastic is caused depending upon the increase of slips of the tape.
In the case of the video tape cassette, plastic powder formed by the wearing phenomenon deposits on the magnetic layer of the tape whereby a drop-out is induced. This is the fatal defect for the video tape cassette. In order to prevent these troubles, a pin mounted on a plastic case is formed instead of the fixed pin and a metal pipe is fixed on the pin in the conventional video tape cassette.
In general, the conventional metal pipe is prepared by cutting and grinding a metal rod.
Many steps are required for cutting and grinding the metal rod so as to necessitate a high cost. In order to overcome the disadvantage of the conventional tape cassette, the inventors have proposed new type tape cassette in our previous application (Japanese Utility Model Application No. 106792/1976).
This structure will be illustrated.
The guide is different from the above-mentioned roller and is not rotated and accordingly, it is not always necessary to have smooth surface for all cylindrical surfaces. That is, the surface which is not contacted with the tape need not be smooth. Accordingly, the guide can be formed by bending one sheet of a plate in a cylindrical shape and the seam i.e. the slit is disposed to the position on which the tape is not contacted.
The cylindrical guide is prepared by processing a plan sheet. It is preferable to use a plate which is relatively flexible and anticorrosive. For this purpose, a stainless steel sheet is usually used.
These sheets have relatively low hardness so as to be difficult to obtain a smooth surface having no mar by polishing the surface.
When fine mars remain after the polishing treatment, the tape is shaved by the mar to cause the drop-out.
When a processible hard substance is used, this trouble can be dissolved. However, crackings are formed in the step of bending the hard sheet in the cylindrical form. Accordingly, it is impossible to use such processible hard substance in practice.